Magnum PI

Hi, wondering if anyone can point me in the right direction.

Car has an intermittantly occuring issue, ill try and explain it the best I can, but bear with me, as it doesn't do this all the time;

Car is a 2002 Focus 1.6 Chic, 1.6 zetec engine.

When the car has warmed up and its at tickover, sometimes the engine can 'bounce' between 750 rpm & 1250 rpm, the rev counter needle will fluctuate between the two speeds, for about a minute then settle down.
This happens after the car has been driven and usually occurs when stopping at traffic lights. its goes like this;
sometimes, on approach to a set of lights you dip the clutch, the engine revs can fall to the point when it feels like the engine will stall (circa 500 rpm), then goto normal idle speed (750-800rpm), then start bouncing between 750 - 1250/1500 rpm.

When the engine is under load, eg, at night, with the lights on, the headlights and speedo lights etc will flicker when the engine is at tickover speed.

The car drives perfectly, the alternator is fine and is charging the battrery. its just that occasionally it'll perform the above weird trick.

any ideas as to what could be causing this would be appreciated.

Thanks in advance

andy

RichieST

iTrader: (2)

Idle control valve most likely, easy to change on the zetec-se engine.

JamesH

iTrader: (21)

Can be a whole host of lovely things, but ISCV is most likely

ScORTED

try unplugging the vss and attempt to replicate it... cleaning the iscv is a good place to start (soak it in carb clean over night then a bit of wd-40 in it) also worth checking the earths in your engine bay for corrosion if you have electrical wobbles

Magnum PI

Thanks for the replies chaps.

I'll give the Idle speed control valve a clean by soaking in carb clean overnight for starters and go from there.

Engine bay is pretty tidy and I've never noticed any rust.....yet.....but it'll be worth checking the earting points too just in case.

Thanks again guys, its greatly appreciated!

martysmartie

iTrader: (1)

Doubt it's the ISCV but do the mentioned anyway as it's free, that is only needed if the ISCV is jamming, the fact your revs are going up and down shows something is telling it to do so.

I would think it's perhaps the VSS, again easy to test simply drive along at around 10MPH and drop into neutral AND release the clutch, the revs should raise to around 1200 RPM, if it does this it shows it to be working.

Martin

RichieST

iTrader: (2)

If it was the VSS, the speedo wouldn't be working?

Magnum PI

Hi the VSS appears to be fine as the car does as described in your 2nd paragraph above.

I couldn't find any carb cleaner, but I have had the ISCV off the car today and gave it a good clean with WD40. It does appear to have made a slight improvement, as at tickover, i feel that the engine idles a bit smoother.

I've also wd40'd all the earthing points in the engine bay.

Before I did this I was always of the opinion that the engine idled pretty 'rough', even though its got full main dealer FSH & i do look after it on a 'no expense spared' basis. I am a bit on the anal side when it comes to vehicle maintenance

at idle before I cleaned the ISCV it was making my glove box rattle!.

Still think it could be improved a bit more though.....

I may also change the HT leads for the hell of it, always fancied getting uprated ones anyway

martysmartie

iTrader: (1)

Fair enough, only time will tell I suppose when you drive it...

Martin

Magnum PI

Update.

I have managed to get hold of some carb cleaner & cleaned the ISCV out.
I have also replaced the rubber gasket that sits behind it as the one that was there looked pretty crusty.

It hasn't performed the flicking between 800 - 1250RPM trick yet, but it still feels like it could be idling a bit smoother.

I have a set of Magnecor 8mm HT leads on order, as I'm going to see if it makes a difference, paid Ł45 for them.
Mr Ford wanted Ł17.50 per HT Lead!! (well 3x Ł17.50 + 1 x Ł18.50) = Ł71 for the set

martysmartie

iTrader: (1)

Keep us posted on how you get on, not to sound pessimistic but I personally do not like the Magnecor leads, I had a set (Not on a Focus) and they caused problems, fair enough it may have just been them as they were getting on a bit, but I also spoke to a tuner who said he had no end of problems with them.

Martin

RichieST

iTrader: (2)

I agree, zetec's don't seem to like aftermarket plugs and leads. Always stick with genuine.

You'd get a set a lot cheaper from a Ford specialist than direct from ford.

dieseldog

i also have this problem, not with the boucing problem, but the anoying drop off of the revs when dipping the clutch and it nearly stalls.

i could try the same on my idle control valve, but where is it please.

rich

phil_focus

i don't know were all this "zetecs don't like different plugs and magnecore leads" is coming from. i've always used ngk platinum plugs in my zetecs (1.6 1.8 and 2l zetec e's) with no problems and i have magnecore kv85 leads on my 2l focus and they improved the smoothness of the engine over the 10 year old shagged ford leads.

i can only imagine the ones with problems either had other issues or the leads were faulty/damaged.


Magnum_PI. good luck fixing it, hopefull you've got it sorted now. the vss is normaly the cause for revving when pulling upto junctions and dipping the clutch. it can also cause the speedo to read zero when driving but it can still be duff and not cause the speedo problem.

Magnum PI

Rich,

The ISCV sits in a different position depending on the engine. on the 1.6 Zetec SE it sits just to the left of the pipe that links the air filter box to the sensor at the engine end.

you will see a silver cylindrical shape bolted to the engine with what can be described as a 50p shaped piece connecting it to the engine.....

Cheers for the help/comments everyone and I will keep updating this thread

after cleaning my ISCV its getting better, but could still be smoother.
When under load ie with headlights on, the speedo clock lights still flicker a little bit at idle speed, along with the headlights and it could still be idling a lot smoother. so not quite happy enough yet, but hoping to get there eventually

I'm renewing the HT leads, then i'll do the coil pack. (even though its not got a misfire).

I've also put a full tank of fuel in with a bottle of injector cleaner in it today, to see if the injectors need a blast out to aid it.....but i tend to use the super unleaded rather than normal....

i'm determined to get to the bottom of it lol

VSS - I assume this is the Vehicle Speed Sensor???

dieseldog

yea cheers for that.

listen, i'm no expert, but in my limited knowledge tell me that if the electrical system is struggling with the lights at idle(but getting brighter when revved i take it), then either its a problem with the alternator, or as mentioned earlier a bad earth. ive noticed focuses do tend to hold a bit of rust here and there. have you also checked the battery connections, it's surprising how much power is lost through the terminals if loose or not properly greased up.

martysmartie

iTrader: (1)

Correct, the Focus lights do flicker momentarily a lot of cars do this, it's not really noticeable though, when coming to a stop etc and the engine sound changes with a heavy electrical load on these, so long as the correct idle speed is maintained there is nothing to worry about

Martin